OPTICAL FREQUENCY COMBS

PRECISION TOOL FOR RESEARCH & INDUSTRY - APPLICATION EXAMPLES
397 nmCold Atoms

543 nmLength Metrology© Rainer Blatt, Innsbruck University, Austria

Optical frequency combs are used to replacetransfer cavities and absorption spectroscopy cells in cold atom experiments. A prominent example is the laser cooling transitionin 40Ca+ at 397 nm, where a direct lock of
the cooling laser to a frequency comb is performed. This results in higher accuracy andstability than with previous methods. Further,it offers much higher flexibility in regard tofuture requirements.

698 nm
Optical Clocks© Christian Lisdat, PTB, Germany

In precision length metrology National
Metrology Institutes worldwide use Menlo
Systems optical frequency combs to traceback the Helium-Neon laser wavelengths at
543 nm and 633 nm to the SI-second. In theactual measurement, interferometers use
both wavelengths simultaneously to measure absolute distances over several ordersof magnitude. Having the lasers stabilized to
the frequency comb allows for highest accuracy and stability.

The quest for the most accurate clock is anextreme challenge. Leading groups are using
Menlo Systems optical frequency combs. In
the measurements, they compare distantclock transitions in the ultraviolet, visible, andinfrared via the frequency comb to determine
which clock has the best stability and accuracy, and improve the current standard. Currently, the strontium lattice clock is one candidate in the race for the world record in stability.
[Bloom et al., Nature 506, 71 (2014),
Falke et al., New J. Phys. 16, 073023 (2014),
Ushijima et al., Nat. Photonics 9, 185 (2015)]© Tilman Pfau, Stuttgart University, Germany

With an optical frequency comb any frequency in the visible and infrared can begenerated. Only a small amount of laser
light is required for the lock to the frequency comb, and it couldn’t be simpler.
For example, 87Rb atoms require light at
specific wavelengths around 480 nm topump the atoms into the Rydberg state.
With the frequency comb, any laser wavelength required can be selected and thus
any level be populated.

Optical frequency combs are inevitable for fundamental tests of various physical quantities.
A prime example is the comparison of radiofrequencies with optical clock transitions. In
2015, 2016, and 2018 Menlo Systems frequency combs were on board of TEXUS sounding rockets. During the flights, all systems had
to withstand conditions of 13 g of acceleration
before experiencing 360 s of microgravity. Einstein’s Equivalence Principle was verified usinga Rubidium clock at 780 nm. For final proof,after the landing with 40 g impacts, the combs
were recovered and found ready to go again.
[Lezius et al., Optica 3, 1381 (2016)]

Rydberg Atoms
480 nmRocket Science780 nm

f1972 nm
Nobel Prize

380 - 2400 nmAstroCombs

The Nobel Prize in Physics 2005 was jointly
awarded to co-founder of Menlo Systems,
Prof. Theodor W. Hänsch and Prof. John L. Hall
“for their contributions to the development oflaser-based precision spectroscopy, including
the optical frequency comb technique”. The
honored measurements included high resolution spectroscopy on hydrogen atoms using
972 nm lasers and frequency combs. Latest
achievements now even allow to perform similar measurements on anti-hydrogen in order toimprove our understanding of the relationshipbetween matter and anti-matter.

Precise calibration of astronomical spectrographs allows for gravitational red-shift detection of stars on the order of cm-1. By using
the spectrally flat, evenly spaced output of aMenlo Systems AstroComb, the most precise
telescopes on earth are improving their ability
to detect exoplanets. Each AstroComb is precisely adapted to the telescope, e.g. offering
18 GHz mode spacing adapted to the resolution of the Echelle spectrometer. AstroCombs
hold many advantages compared to other calibration sources, such as thorium-argon lamps
or Fabry-Pérot interferometers. Most importantly, they allow for an absolute calibration.

f2

Lasers operating in the telecom range at
1550 nm and linked to stable optical clocks
allow for the dissemination of ultrastablefrequencies via optical fibers. Using opticalfrequency combs on both ends of the fiberconnections and technologies for noise
cancellation resulting from fiber lengthchanges, stabilities better than 10-16 in one
second have been achieved in fiber networks over hundreds of kilometers.
[Predehl et al., Science 336, 441 (2012)]

In medicine, non-invasive and instantaneous determination of diseases canbe performed by carefully analyzing thebreath of a patient. Diseases ranging fromdiabetes to smallpox have molecular signatures that can be analyzed in real-timeusing frequency comb spectroscopy in theinfrared. By shifting the output of a frequency comb via nonlinear optics, any
wavelength required for the analysis canbe generated.

The field of mid-infrared spectroscopy isgrowing rapidly. Astrochemistry, plasma physics, molecular spectroscopy, and other disciplines are benefitting from absolute frequency
measurements between 1 and 15 µm using
optical frequency combs. From standard frequency combs, offset-free DFG frequencycombs, to dual comb systems, the Menlo Systems portfolio offers the best frequency comb
for any application covering all wavelengths
from NIR to mid-IR.

Optical Networks

Breath Analysis

Mid-IR Spectroscopy
1-15 µm

1550 nm1600 - 1900 nm

PRECISION IN PHOTONICS. TOGETHER WE SHAPE LIGHT.

Menlo Systems GmbH is a leading developer and global supplier of instrumentation for high-precision metrology. The company with headquarters in Martinsried near Munich is known for its Nobel Prize winning opticalfrequency comb technology. With subsidiaries in the US and China and a global distributor network, Menlo Systems is closely connected to its customers from science and industry. The main product lines are optical frequency combs, time and frequency distribution, terahertz systems, ultrafast and ultrastable lasers, and corresponding control electronics. Besides standard production, Menlo Systems develops and manufactures custom made solutions for laser-based precision measurements.

Menlo Systems GmbH
Bunsenstraße 5D-82152 Martinsried
Germany
T+49 89 189 166 0
F+49 89 189 166 111sales@menlosystems.com
www.menlosystems.com

Menlo Systems, Inc.
56 Sparta Avenue
Newton, NJ07860
USA
T+1 973 300 4490
F+1 973 300 3600
ussales@menlosystems.com

Thorlabs, Inc.
56 Sparta Avenue
Newton, NJ07860
USA
T+1 973 579 7227
F+1 973 300 3600
sales@thorlabs.com